Minneapolis Park & Recreation Board

Discussion Item
2681

Bridges at Kenilworth Channel

Information

Department:Planning ServicesSponsors:
Category:Discussion

Body

BACKGROUND

 

When the Board of Commissioners approved a Memorandum of Understanding (MOU) between the Minneapolis Park & Recreation Board (MPRB) and the Metropolitan Council regarding the crossing of the Kenilworth Channel by the Southwest Light Rail Transit (SWLRT) project, it initiated a design process for bridges over the channel that would carry freight rail, light rail, and pedestrians and bicycles. The MOU included a description of a collaborative process the Southwest Project Office (SPO) and MPRB would follow to arrive at an acceptable design for the bridges. The description of the process noted several factors the bridge design process would consider in arriving at concepts, and provided for updates to the Board of Commissioners as a means of gaining additional insights that would lead to an acceptable design.

 

MPRB and SPO staff have been meeting weekly since the execution of the MOU. During that time, a wide range of configurations and design concepts has been developed. Focus has been directed to several key considerations:

 

·          Creation of a trail bridge that is separate from the LRT bridge

Initial options for the Kenilworth bridges showed a freight bridge and an LRT/trail bridge. Because loading and deflection requirements vary greatly between the needs for LRT and the trail, the potential for separation was investigated and it was determined that separate structures could be achieved.

 

·          Definition of pier and span configurations that minimize impacts upon the channel

Initial options for the Kenilworth bridges relied upon thinner bridge decks that required more piers in the channel. Current options optimize deck thickness related to piers, resulting in longer spans and fewer piers and create a more open channel.

 

·          Exploration of methods to bring light to the channel

While reducing the width of bridge decks is not possible, separating the trail bridge from the LRT bridge creates an opportunity to increase light penetration to the channel. Creating a slight skew for the trail bridge (shown in one of the options) also affords an opportunity to change the way light reaches the channel. The designers are exploring the potential of changing surface materials for required walkways on the freight and LRT bridges to create opportunities for even more light to reach the channel, however those methods may also create paths for LRT-generated noise to reach the channel.

 

·          Exploration of methods to limit noise impacts to channel users

The generation of noise for LRT vehicles is focused on a zone near the wheels. The LRT bridge designs are beginning to look at methods to contain noise within low walls at each edge of the bridge.

 

Bridge designs also provide space on one side of the channel to accommodate a six-foot wide trail. Such a trail will not be implemented with the construction of the bridges or SWLRT, but will allow the MPRB to construct a trail at a later date.

 

Many permutations of pier and span configurations and design directions have been framed through staff work sessions. Initial configurations and design directions were shared during a Section 106 consultation session, for which official comments will be received from consulting parties by May 27, 2015. The range of options was narrowed based on the Section 106 consulting party review, construction feasibility, alignment with criteria set by MRPB and SPO, compatibility of structures with the qualities of the channel and, in particular, accommodation of trail and channel users.

 

 

RECOMMENDATION

 

This item is for discussion purposes.

 

Meeting History

May 20, 2015 5:00 PM  Minneapolis Park and Recreation Board Regular Meeting

President Wielinski called upon Michael Schroeder, Assistant Superintendent Planning to discuss Kenilworth Channel Bridge options with the Board.